﻿<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0, user-scalable=0, minimum-scale=1.0, maximum-scale=1.0">
<meta name="apple-mobile-web-app-capable" content="yes">
<meta name="apple-mobile-web-app-status-bar-style" content="black">
<script src=""    charset="utf-8"></script>
</head>
<body>
<button onclick="loadScript('http://code.jquery.com/jquery.min.js',function(){alert('加载成功')})"  type="button">异步加载js</button>




		
		
<script>
	function loadScript(url, callback){
		var script = document.createElement ("script")
		script.type = "text/javascript";
		script.onload = function(){
			callback();
		};
		 
		script.src = url;
		document.getElementsByTagName("head")[0].appendChild(script);
	}

</script>
</body>
</html>